Though some studies have indicated that Phenacomys ungava is "rare" or "uncommon," other researchers have found that the animal can be common locally, and others have suggested that the population may undergo cyclic abundance.

They are very similar in appearance to the western heather vole, and can only be distinguished from them by subtle features of the coat color and the shape of the skull.

The coat is brownish with a slight yellowish wash over the back and head, with pale grey underparts and feet, and brighter, almost russet, fur on the rump and flanks.

Four subspecies have been recognised,[4] although these are not universally accepted:[5] They are most commonly found in coniferous forests dominated by pine and spruce, usually in areas with heavy undergrowth.

[7] Eastern heather voles are herbivorous, feeding on plant leaves and berries, especially blueberries, in summer and the bark, seeds, and buds of willows and shrubs in winter.

[8] They are among the few vertebrates capable of eating the bark of sheep laurel, and may play an important ecological role in recycling nutrients from this otherwise toxic source.